The disclosure relates to an arrangement for detecting connection loss at a circuit part having a capacitive behavior and to a method for detecting connection loss at a circuit part having a capacitive behavior.
Safety-critical wire bonds with a monitoring system are provided in known rotation rate sensors for motor vehicles. The principle according to which said system functions is based on a current source that supplies a small measuring DC current to the bond, which current then flows back by way of another bond. It is not possible to maintain the current flow where one of the two bonds is disconnected or interrupted and a disconnection and/or interruption of this type can be recognized in that, for example, an error flag is set that signals a disconnected and/or interrupted bond. However, the described procedure of detecting a bond connection loss cannot be used to monitor bonds that are connected to a circuit part having a capacitive behavior owing to the fact that it is not possible to supply a DC measuring current. Therefore, some safety-relevant bonds cannot be monitored.
The unexamined German application DE 10 2004 026 971A1 describes for example a micromechanical sensor with error recognition. The described sensor comprises a micromechanical functioning part and an electronic evaluating circuit that are mutually electrically connected. In addition, means for performing a self-diagnostic test on the sensor are provided in such a manner that error recognition of at least one electrical connection is achieved. During the self-diagnostic test, an excitation module transmits a signal pattern to the micromechanical functioning part. A measuring signal is then produced that is converted by a signal evaluating module into a sensor output signal. In addition to the test signal, the excitation module provides also a correlation signal. The correlation signal and the sensor output signal are conveyed to a demodulation module in which a correlated demodulation of the signals takes place. A demodulated output signal is conveyed to an evaluating module in which on the basis of the evaluated signal pattern the condition of the at least one electrical connection is finally evaluated and a corresponding signal is output.